With the rapid development of display technology, liquid crystal display devices (such as a liquid crystal TV, a liquid crystal display, a liquid crystal display panel) are widely used in production and human life due to its low voltage driven, flat panel structure, more information displayed, easily colorized, durability, less radiation and pollution.
However, a liquid crystal display (LCD) device is a passive display device, and it is required to modulate external light to display as it can not emit light itself. With the continuously increasing area of the liquid crystal display panel, side light type can not meet the requirement of the liquid crystal display device any longer, because its backlight module is limited by optical path and so on. A direct backlight module is more suitable for a big size LCD device due to its flexible lamps configuration and control, and so on. However, the direct backlight module generally has a great thickness and needs numerous of light emitting diodes (LED), which increases the cost for the LCD device.